Free-bound excitation and predissociation of ytterbium dimers near the ¹S₀-¹P₁ atomic transition

A continuous excitation band of a free-bound photoassociation transition of ytterbium atoms is observed as a red wing of the ¹S₀-¹P₁ atomic line at 399 nm for a hot thermal vapor. The excitation to the 0u⁺ molecular state is observed by monitoring fluorescence from the ³P₁ state atoms, which allows us to detect the production of Yb₂ molecules with high sensitivity. The photoassociation is characterized in comparison with transitions to atomic Rydberg states. The time profile of the fluorescence signal suggests that the 0u⁺ molecular state predissociates with states correlating to the ¹S₀+³D₂ atomic states.